The invention concerns machinery safety guards, and has more particular, though not exclusive reference to guards for machines which employ a rotating cutter or like tool rotating about a vertical axis, such as milling machines or drilling machines.
Guards are known for use with drilling machines which comprise a part-cylindrical, transparent shield intended, when in a position of use, to be disposed coaxially with the drill bit, the shield extending partially around such bit in the peripheral direction thereof. In order to provide ready access to the chuck for the purpose of drill inspection, drill changing or the like, or to facilitate inspection of the workpiece, the shield is movably mounted on a ring secured to the quill or barrel of the drilling machine, being adjustable between a first, or operative position, wherein the shield and drill bit are arranged in coaxial relationship, and a second, or inoperative position, wherein the shield is pivoted upwardly and away from the drill bit about an horizontal axis transversely of the axis of the drilling head, against the restraint of spring means, the spring means holding the shield in one or other of the two extreme positions when in such position.
Other arrangements are known wherein the shield is pivotal about a generally vertical axis as defined by one or more hinges provided at a lateral edge of the shield and whereby such shield is mounted on a guard body.
Whilst the guards as aforesaid are effective in offering protection to the drilling machine operator when in an operative position, a guard may, inadvertently or otherwise, be left in an inoperative position, being held in such position by spring means, and the machine operated with the shield in such position.